Grain drills or seeders such as air seeders for crop farming are typically mounted on a trailer towed behind a tractor or other farming machinery. An air seeder generally comprises a toolbar having ground openers mounted thereon for receiving and delivering seed and/or seed/soil supplement product such as fertilizer into or on the ground. The seeder may include at least one seed and/or seed/soil supplement product frame-mounted hopper or tank for storing seed and/or supplement product in granular form to be planted or spread over farmland. In the alternative, a separate product dispensing cart (e.g., an air cart) can be towed behind the seeder for holding and dispensing product to the seeding tools of the seeder. Supplement product includes, but is not limited to, fertilizer, inoculants, herbicide, etc. The seed and supplement product will generally be referred to herein as product.
Air seeders typically employ a metering system for dispensing product from the hopper and a pneumatic distribution system for delivering the metered product to the soil. Air seeders that can separately meter seed and supplement product are available having distribution systems that can apply both seed and supplement product such as fertilizer simultaneously to a field.
A metering system for an air seeder generally includes a volumetric meter that may be geared to the wheels of the air seeder trailer or product dispensing cart as known in the art to dispense a fixed volume of product per unit of linear distance traveled by the air seeder. A volumetric meter typically includes either augers or a fluted cylinder (meter roller) mounted at the bottom of the hopper, product from the hopper filling the interstitial spaces thereon. Rotating the volumetric meter against a screed measures out the granular product in units of interstitial volumes. Thereafter, the product so dispensed is allowed to enter the pneumatic distribution system. Thus, the volumetric meter is driven by a ground wheel such that the meter turns proportionally to the ground wheel and the rate of delivery of product will remain constant regardless of the speed of the seeder.
The pneumatic distribution system generally utilizes air under pressure to provide at least one air stream that flows through the pneumatic distribution system and carries the product to be deposited in the soil, typically by seed boots. Product dispensed by the metering system is first introduced into the air stream at a primary distribution manifold. Fluidized product is carried under air pressure by primary distribution lines to a group of secondary distribution manifolds (“headers”), which in turn distribute product through secondary distribution lines to individual seed boots mounted behind ground openers on the tilling implement. The metering of the product dispensed may evenly deliver the product along a furrow made by a corresponding opener of the tilling equipment.
Seeding at the proper rate and desired depth are essential for obtaining maximum yield of crop. However, the size of seed and supplement product will vary between varieties and even the size of seed of the same variety may vary from one year to the next. This requires that a seeder metering system be calibrated so that the correct amount of seed is planted. Because most metering systems are based on a volume displacement, if one lot of seed varies in size and weight from another, two different amounts or number of seeds will be metered if the meter settings are not changed.
Air seeder manufacturers generally include a calibration method in their operator's manual. Such calibration generally requires collecting a unit of product from each meter and weighing the unit of product. This is routinely done when the seeder is stationary by providing a handle or crank for rotating the volumetric meter against the screed a given number of times for a particular area and then collecting the product dispensed in a bag, pail, catch box or the like. Such crank can be hand operated or operate using an electric or hydraulic motor. The number of turns of the meter is generally determined by a sensor located at the meter. The collected product is then weighed using a scale. The average product per square foot or product per lineal foot is then calculated and the metering system is set accordingly. An example of a seeder calibration apparatus and method that uses a hydraulic motor is described in Canadian Patent No. 2,311,698, incorporated herein by reference.
Most seeders are equipped with a calibration console (monitor/control) having an input device (e.g., key pad) for inputting data such as the weight of the unit of product collected and a microprocessor that will automatically perform the calculations for each metered product and provide the operator with the product application rate (weight of product dispensed per unit of area covered by the seeder). The metering system can then be adjusted accordingly to vary the rate of delivery of a product to be dispensed. Unfortunately, such calibration consoles are only located in the cab of the tractor. It is not uncommon for an operator to have to calibrate a metering system more than once during a given operation. Furthermore, if dispensing more than one product, such calibrations must be done for each metered product.
Thus, depending upon the number of times an operator is required to calibrate a particular product and the number of individual products being dispensed in a given operation, the operator may need to make several trips to the tractor cab from the seed cart where the metering system is located while remembering the exact weight of the calibrated product. This is very time consuming and leaves a potential for errors. Some of the products to be applied are expensive and thus an error in application rate can be very costly.
Therefore, there is a need in the crop farming industry for a method and apparatus for calibrating a metering system that is convenient for the operator and provides less room for operator error.